UV Lights Up Marine Fish

Considering that water more strongly attenuates electromagnetic radiation of longer wavelength, it's not surprising that fish don't necessarily "see" the same wavelengths that human beings do or that they are adapted to respond to various frequencies in different ways. Studying species from tropical reefs, the authors learned that many fish are able to see radiation into the ultraviolet portion of the spectrum. Further, they discovered that the mucus so common to the skin of reef denizens is actually a very effective sunscreen.